ATLANTA — Ivan Johnson knows the Hawks are probably his last chance to make a good impression on the NBA.

Not many 27-year old rookies get a second chance.

So far, so good.

After the 6-foot-8, 255-pound banger knocked around the minor leagues trying to overcome a reputation as a hothead, Hawks forward Josh Smith says Atlanta has found a “diamond in the rough”

Johnson said his past separates him from other rookies.

“Some of these players coming straight out of college haven’t been through a lot of stuff,” Johnson said. “I’ve been through a lot. I know what hard work means.”

Johnson spent last season with Erie of the NBA D-League after playing professionally in China, South Korea and Puerto Rico.

He was released from his scholarship at Oregon in 2006 after being benched for what was called improper displays of attitude. He finished at Cal State San Bernardino in 2007.

Then anger-related incidents earned him a ban from the Korean Basketball League. He said it was the most difficult place for him to play.

“They work hard over there. Lots of running,” Johnson said. “Then the coaches get mad if you want to take a break or something. They’d be quick to cut you over there.”

Not in Atlanta where big men are scarce.

Johnson has become a key backup and favorite with fans who Monday night chanted “I-van Johnson! I-van Johnson!” during the Hawks’ loss to the Phoenix Suns.

Asked how he’s won over the fans, the normally stern-faced Johnson allowed a small smile and said “I’m a beast. I keep working hard. I’ve got a lot of heart.”

Those qualities also have won over Hawks coach Larry Drew, who was as surprised as anyone to see Johnson make the team in camp.

The Hawks waived their only draft pick, center Keith Benson, to keep Johnson.

He proved to be a key member of the Hawks’ rotation after All-Star center Al Horford was lost for at least three months with a torn pectoral muscle and backup Jason Collins sprained his left elbow last week.

Collins is expected to miss at least two weeks, leaving Johnson as the slightly undersized backup to Zaza Pachulia at center. The burly Johnson, equipped with ample bulk and more than ample energy, has been productive with his minutes.

Johnson posted a double-double with 14 points and 13 rebounds against Philadelphia on Saturday night. He had nine points and five rebounds in 15 minutes against Phoenix on Monday night.

Making presence known

“He’s responded very well,” Drew said. “I’m surprised. He carries himself as a veteran. He doesn’t have any fear about going against guys who are bigger and faster.

“When he’s in the game, you know he’s in the game because he throws his body around. He’s on the offensive glass. He gets to the basket.”

Johnson played like he belonged from the first day of camp.

“He definitely caught a lot of guys’ eyes when camp started,” said Smith, who has assumed a mentor role with Johnson. “Just his aggressiveness, his physicality. There was no backing down when he was on the post. Guys respected that because a lot of guys come in timid.”

Johnson said he was hardened by his experiences the last few years, especially overseas.

He earned the invitation to camp by averaging 22.6 points and 7.6 rebounds with Erie last year. He made the first-team All-D League.

Johnson has helped keep the Hawks near the top of the Southeast Division, despite a three-game losing streak.

Smith, one year younger than Johnson, is in his eighth year in the league. He shook his head when talking about Johnson’s unique opportunity.

“For him to create a new path for his career like that, I’m just real happy to see that,” Smith said. “I just like guys that play hard and fear no one. That’s the type attitude he has.”

After fans chanted Johnson’s name on Monday night, Drew quickly responded by sending the power forward into the game. As has been his norm, Johnson provided immediate results. He delivered a basket followed by an offensive rebound and put-back for another score.

He has modest averages of 6.0 points and 4.0 rebounds for the season, but he has averaged 11 points and nine rebounds in three games this month.